What is screening constant for outer electron of H?

Answer

To determine the screening constant (σ) for the outer electron of hydrogen (H), we need to follow these steps:

### Step 1: Understand the Definition of Screening Constant
The screening constant (σ) is defined as:
\[ \sigma = Z - Z^* \]
where:
- \( Z \) is the atomic number of the element.
- \( Z^* \) is the effective nuclear charge experienced by the outermost electron.

### Step 2: Identify the Atomic Number of Hydrogen
For hydrogen (H), the atomic number \( Z \) is:
\[ Z = 1 \]

### Step 3: Determine the Effective Nuclear Charge
For hydrogen, there is only one electron, and it is in the outermost shell. Therefore, the effective nuclear charge \( Z^* \) is also:
\[ Z^* = 1 \]

### Step 4: Calculate the Screening Constant
Now, we can substitute the values of \( Z \) and \( Z^* \) into the formula for the screening constant:
\[ \sigma = Z - Z^* \]
\[ \sigma = 1 - 1 \]
\[ \sigma = 0 \]

### Step 5: Conclusion
The screening constant for the outer electron of hydrogen is:
\[ \sigma = 0 \]